The present invention is generally related to materials that are used in the field of packaging or structural applications, such as syntactic foams, and is more specifically related to materials that have properties, such as dielectric constants, that may be tailored so as to be useful in such applications.
The dielectric constant is an important property in electronic substrate or packaging applications. Materials that have a possibility of tailoring their dielectric constant may be very useful in such applications. In addition, an increase in temperature during the usage of electronic components may be a challenge that may lead to thermal stresses and failure. Syntactic foam composite materials have been employed in such applications.
Very large scale integration of electronic circuits has drastically reduced the size of circuit boards used in electronic devices. This has created a desire to develop materials with low dielectric constant, high specific strength, low density, low moisture absorption and high durability. Integrated circuit boards, which form the heart of computers, require electrical insulators with low and preferably tunable dielectric properties. Polymers and polymeric composites have found applications in such fields due to their low dielectric properties.
Epoxy resins, which are often used as matrix materials for composites, may also be used in electrical and electronic fields as insulators, dielectrics and as underfills in circuit boards. One of method of decreasing the dielectric constant of the polymer is to introduce porosity in the polymer. Since air has a low dielectric constant of 1, the dielectric constant of polymer foams is low and may also accompany low strength and stiffness, which are undesirable. In addition, irregular size and distribution of gas voids in polymer foams may lead to mechanical property variation within the material.
The instant inventors are not aware of an instance where the dielectric constant and the coefficient of thermal expansion of a syntactic foam have been tailored simultaneously. Accordingly, there is a need for a syntactic foam composite material that may be simultaneously tailored for multiple properties, such as dielectric constant, coefficient of thermal expansion (CTE), and density,